A protein is one of main substances constituting an organism, and has been widely used as a medical product, a medical material or the like. Conventionally, a protein to be used has been obtained by various methods (e.g. purification of a protein from a natural material). In recent years, a method for forcibly expressing a target protein in various kinds of cells has been used, and such protein has been used in various ways. However, such a conventional method undesirably requires complicated steps to purify a desired protein from a cell. Further, a great amount of protein is required in some applications. However, such a classical method unfortunately cannot produce a large amount of protein.
Various methods have been developed which allow easy purification of proteins which are forcibly expressed in various kinds of cells. Examples of such methods include a method in which a fusion protein having a tag of various kinds attached thereto are forcibly expressed in various kinds of cells, respectively, and then the fusion proteins are purified by adsorption between the tag and a carrier having affinity with the tag. Until now, various kinds of tags have been developed. Examples of such tags include a GST protein, an HA tag, a Flag tag, a Myc tag, and a His tag.
Citation List
Patent Literature 1
WO2007/055288 Pamphlet (Publication Date: May 18, 2007)
Non-Patent Literature 1
Taniguchi, K. et al., The Si-tag for immobilizing proteins on a silica surface. Biotechnol. Bioeng. 96: 1023-1029 (2007)
Non-Patent Literature 2
Fuchs, S. M. and Raines, R. T. Polyarginine as a multifunctional fusion tag. Protein. Sci. 14: 1538-1544 (2005)
Currently, functional analysis of various kinds of proteins is in progress, and such tags are used in examining interaction between plural proteins. Since the analysis needs to be conducted from many different perspectives, wider variety of tags used for protein purification are better.